Calmodulin and PF6 are components of a complex that localizes to the C1 microtubule of the flagellar central apparatus

Studies of flagellar motility in Chlamydomonas mutants lacking specific central apparatus components have supported the hypothesis that the inherent asymmetry of this structure provides important spatial cues for asymmetric regulation of dynein activity. These studies have also suggested that specific projections associated with the C1 and C2 central tubules make unique contributions to modulating motility; yet, we still do not know the identities of most polypeptides associated with the central tubules. To identify components of the C1a projection, we took an immunoprecipitation approach using antibodies generated against PF6. The pf6 mutant lacks the C1a projection and possesses flagella that only twitch; calcium-induced modulation of dynein activity on specific doublet microtubules is also defective in pf6 axonemes. Our antibodies specifically precipitated five polypeptides in addition to PF6. Using mass spectrometry, we determined the amino acid identities of these five polypeptides. Most notably, the PF6-containing complex includes calmodulin. Using antibodies generated against each precipitated polypeptide, we confirmed that these polypeptides comprise a single complex with PF6, and we identified specific binding partners for each member of the complex. The finding of a calmodulin-containing complex as an asymmetrically assembled component of the central apparatus implicates the central apparatus in calcium modulation of flagellar waveform

GbdR Regulates Pseudomonas aeruginosa plcH and pchP Transcription in Response to Choline Catabolites

Pseudomonas aeruginosa hemolytic phospholipase C, PlcH, can degrade phosphatidylcholine (PC) and sphingomyelin in eukaryotic cell membranes and extracellular PC in lung surfactant. Numerous studies implicate PlcH in P. aeruginosa virulence. The phosphorylcholine released by PlcH activity on phospholipids is hydrolyzed by a periplasmic phosphorylcholine phosphatase, PchP. Both plcH gene expression and PchP enzyme activity are positively regulated by phosphorylcholine degradation products, including glycine betaine. Here we report that the induction of plcH and pchP transcription by glycine betaine is mediated by GbdR, an AraC family transcription factor. Mutants that lack gbdR are unable to induce plcH and pchP in media containing glycine betaine or choline and in phosphatidylcholine-rich environments, such as lung surfactant or mouse lung lavage fluid. In T broth containing choline, the gbdR mutant exhibited a 95% reduction in PlcH activity. In electrophoretic mobility shift assays, a GbdR-maltose binding protein fusion bound specifically to both the plcH and pchP promoters. Promoter mapping, alignment of GbdR-regulated promoter sequences, and analysis of targeted promoter mutants that lack GbdR-dependent induction of transcription were used to identify a region necessary for GbdR-dependent transcriptional activation. GbdR also plays a significant role in plcH and pchP regulation within the mouse lung. Our studies suggest that GbdR is the primary regulator of plcH and pchP expression in PC-rich environments, such as the lung, and that pchP and other genes involved in phosphorylcholine catabolism are necessary to stimulate the GbdR-mediated positive feedback induction of plcH

Bioengineered Lysozyme Reduces Bacterial Burden and Inflammation in a Murine Model of Mucoid Pseudomonas aeruginosa Lung Infection

The spread of drug-resistant bacterial pathogens is a growing global concern and has prompted an effort to explore potential adjuvant and alternative therapies derived from nature\u27s repertoire of bactericidal proteins and peptides. In humans, the airway surface liquid layer is a rich source of antibiotics, and lysozyme represents one of the most abundant and effective antimicrobial components of airway secretions. Human lysozyme is active against both Gram-positive and Gram-negative bacteria, a

Elucidating the Role of Microbiome in Low- and High-Grade Glioma

https://openworks.mdanderson.org/sumexp22/1117/thumbnail.jp

Impact of a Whole Foods Based High Fiber Diet on Gut Microbiome in Melanoma Survivors

https://openworks.mdanderson.org/sumexp21/1237/thumbnail.jp

Longitudinal trajectories and predictors of adolescent suicidal ideation and attempts following inpatient hospitalization.

Remarkably little is known regarding the temporal course of adolescent suicidal ideation and behavior, the prediction of suicidal attempts from changes in suicidal ideation, or the prediction of suicidal attempts after accounting for suicidal ideation as a predictor. A sample of 143 adolescents 12–15 years old was assessed during psychiatric inpatient hospitalization and again at 3, 6, 9, 15, and 18 months postdischarge through a series of structured interviews and parent- and adolescent-reported instruments. Symptoms of depression, posttraumatic stress disorder, externalizing psychopathology, hopelessness, and engagement in several forms of self-injurious/suicidal behaviors (i.e., suicide threats/gestures, plans, nonsuicidal self-injury [NSSI]) were assessed. Latent growth curve analyses revealed a period of suicidal ideation remission between baseline and 6 months following discharge, as well as a subtle period of suicidal ideation reemergence between 9 and 18 months postdischarge. Changes in suicidal ideation predicted suicide attempts. After accounting for the effects of suicidal ideation, baseline suicide threats/gestures also predicted future suicide attempts. Higher adolescent-reported depressive symptoms, lower parent-reported externalizing symptoms, and higher frequencies of NSSI predicted weaker suicidal ideation remission slopes. Findings underscore the need for more longitudinal research on the course of adolescent suicidality

Longitudinal trajectories and predictors of adolescent suicidal ideation and attempts following inpatient hospitalization.

Remarkably little is known regarding the temporal course of adolescent suicidal ideation and behavior, the prediction of suicidal attempts from changes in suicidal ideation, or the prediction of suicidal attempts after accounting for suicidal ideation as a predictor. A sample of 143 adolescents 12–15 years old was assessed during psychiatric inpatient hospitalization and again at 3, 6, 9, 15, and 18 months postdischarge through a series of structured interviews and parent- and adolescent-reported instruments. Symptoms of depression, posttraumatic stress disorder, externalizing psychopathology, hopelessness, and engagement in several forms of self-injurious/suicidal behaviors (i.e., suicide threats/gestures, plans, nonsuicidal self-injury [NSSI]) were assessed. Latent growth curve analyses revealed a period of suicidal ideation remission between baseline and 6 months following discharge, as well as a subtle period of suicidal ideation reemergence between 9 and 18 months postdischarge. Changes in suicidal ideation predicted suicide attempts. After accounting for the effects of suicidal ideation, baseline suicide threats/gestures also predicted future suicide attempts. Higher adolescent-reported depressive symptoms, lower parent-reported externalizing symptoms, and higher frequencies of NSSI predicted weaker suicidal ideation remission slopes. Findings underscore the need for more longitudinal research on the course of adolescent suicidality.Psycholog

Absence of Membrane Phosphatidylcholine Does Not Affect Virulence and Stress Tolerance Phenotypes in the Opportunistic Pathogen Pseudomonas aeruginosa

During growth in presence of choline, both laboratory and clinical Pseudomonas aeruginosa strains synthesize phosphatidylcholine (PC), and PC makes up ∼4% of the total membrane phospholipid content. In all the strains tested, PC synthesis occurred only when choline is provided exogenously. Mutants defective in synthesis of PC were generated in the strain backgrounds PAO1 and PA14. Minimum inhibitory concentration studies testing sensitivity of PC-deficient strains towards various antibiotics and cationic antimicrobial peptides revealed no differences as compared to wild-type strains. Mutants incapable of synthesizing PC were also found to be unaffected in motility and biofilm formation on abiotic surfaces, colonization of biotic surfaces and virulence in a mouse infection model. A global phenotypic microarray was further used to identify conditions wherein membrane PC may play a role of in P. aeruginosa. No culture conditions were identified wherein wild-type and PC-deficient mutants showed phenotypic differences. Membrane PC may serve a highly specific role during P. aeruginosa interactions with its eukaryotic hosts based on all the clinical strains tested retaining the ability to synthesize it during availability of choline

Step-Wise Loss of Bacterial Flagellar Torsion Confers Progressive Phagocytic Evasion

Phagocytosis of bacteria by innate immune cells is a primary method of bacterial clearance during infection. However, the mechanisms by which the host cell recognizes bacteria and consequentially initiates phagocytosis are largely unclear. Previous studies of the bacterium Pseudomonas aeruginosa have indicated that bacterial flagella and flagellar motility play an important role in colonization of the host and, importantly, that loss of flagellar motility enables phagocytic evasion. Here we use molecular, cellular, and genetic methods to provide the first formal evidence that phagocytic cells recognize bacterial motility rather than flagella and initiate phagocytosis in response to this motility. We demonstrate that deletion of genes coding for the flagellar stator complex, which results in non-swimming bacteria that retain an initial flagellar structure, confers resistance to phagocytic binding and ingestion in several species of the gamma proteobacterial group of Gram-negative bacteria, indicative of a shared strategy for phagocytic evasion. Furthermore, we show for the first time that susceptibility to phagocytosis in swimming bacteria is proportional to mot gene function and, consequently, flagellar rotation since complementary genetically- and biochemically-modulated incremental decreases in flagellar motility result in corresponding and proportional phagocytic evasion. These findings identify that phagocytic cells respond to flagellar movement, which represents a novel mechanism for non-opsonized phagocytic recognition of pathogenic bacteria